The thing is, Apple isn't the first one out of the gate with a unique idea this time. It's basically a large iPod Touch.

Before the iPad was even announced, many other companies had already shown off full screen touch tablets of around the same size that would be shipping this year also. With a plethora of them being shown of back at CES on January 7-10th.

So it's not that people are saying the idea will fail, they are merely saying Apple's attempt will fail. It's over priced and lacks good functionality compared to what competitors will have. And with it being publicly made apparent that Apple is making almost $250 profit on the cheapest model, and close to $500 profit on the most expensive one, has really hurt their chances even more. Because people see they aren't quite getting the hardware specs they'd be expecting for the price.

And Apple's supposedly special A4 processor it uses inside is merely the now quite old ARM Cortex A8, which is in many phones and portable devices already, and lacks good power for a tablet device. It should have been a ARM Cortex A9 dual-core, which is vastly more powerful and is what most smartphone, PMP and tablet manufacturers will be using. Including Nvidia's Tegra 2 platform.